The Data

GMAD contains approximately 50,000 trade records. Each trade record is a total number traded for a unique combination of

• Species (fish, corals, invertebrates other than corals)
• Country of export
• Country of import
• Date (year)

Data Sources

The following organisations and people have contributed data to GMAD:

All are wholesale traders with the exception of four management authorities (*) who gather data from collectors as a condition of their licences.

Essential Information

Just like any database GMAD is entirely dependant on the nature of the data held in it, and of the way that data was collected.

Import and Export Data

GMAD contains sales data from wholesale export and import companies. These data cannot simply be pooled because naturally some of the contributing importers are trading with some of the contributing exporters and so pooling data would create duplications. Therefore GMAD has been designed so that import or export data can only be queried separately. For example, the trade in any (or all) species between any pair of countries has to be calculated from either import data or export data. The advantage of obtaining wholesale data from both ends of the chain of supply is that the import data obtained can be cross-checked against the export data, and vice versa.

For example, if you are interested in the number of powder brown tang (Acanthurus japonicus) exported from the Philippines to the Netherlands. You calculate two numbers the first based on export data, the second on import data. In September 2001 GMAD contained data from 5 Philippine exporters, and import data from 1 Dutch importer and this query would have given you 2151 fish exported and 425 imported. Given the respective sources of the data is probable that the figure based on exports is most representative of the trade in Acanthurus japonicus between these two countries. There are, of course, companies in the Philippines and Netherlands trading in Acanthurus japonicus other than those which have contributed their data to GMAD, and therefore this figure of 2151 fish is just a quantitative total on which to base estimates of the whole trade in this species.

A consequence of this is that GMAD cannot be used to calculate the absolute volume of trade in any one species, or between any pair of countries. However such calculations are based on quantitative data and the degree to which these data are indicative of the trade depends in part on the proportion of operational wholesale export and import companies contributing data to GMAD.

If there are good reasons to believe that companies supplying the same markets do not differ substantially in the species or quantities which they trade then GMAD data may be used to calculate the relative contribution of any species (and indeed country or region) to trade with more certainty. To continue the previous example, seven species of Acanthurus are exported from the Philippines and A. japonicus constitutes 65% of trade in this genus, and 1% of the trade in all fish from the Philippines. If it is possible to assume that the Philippine export companies which have not contributed data to GMAD do not trade in substantially different quantities of this species then these percentages may be taken as representative.

GMAD Structure

GMAD contains some confidential information. For example, there are company specific records held within GMAD but we are not free to distribute these: it is therefore only possible to query GMAD at national, or higher, levels. Likewise some companies have made mortality data available to UNEP-WCMC but on condition that it remains confidential.

These data are held within a central component to GMAD. The species trade data are linked to two external databases:

(1) FishBase, for photographs of fish species, and fish taxonomy, and
(2) the Species Conservation Database for invertebrate taxonomy and relevant legislation (e.g. CITES regulations for corals).